xtables-monitor: fix rule printing

trace_print_rule does a rule dump.  This prints unrelated rules
in the same chain.  Instead the function should only request the
specific handle.

Furthermore, flush output buffer afterwards so this plays nice when
output isn't a terminal.

Signed-off-by: Florian Westphal <fw@strlen.de>

diff --git a/iptables/xtables-monitor.c b/iptables/xtables-monitor.c
index 4008cc00d4694d0dd368f46686828e1528e8341c..364e600e1b38af7df6171f8cc3d215e4acc68680 100644 (file)
--- a/iptables/xtables-monitor.c
+++ b/iptables/xtables-monitor.c
@@ -227,12 +227,12 @@ static void trace_print_rule(const struct nftnl_trace *nlt, struct cb_arg *args)
                exit(EXIT_FAILURE);
        }
 
-       nlh = nftnl_chain_nlmsg_build_hdr(buf, NFT_MSG_GETRULE, family, NLM_F_DUMP, 0);
+       nlh = nftnl_chain_nlmsg_build_hdr(buf, NFT_MSG_GETRULE, family, 0, 0);
 
         nftnl_rule_set_u32(r, NFTNL_RULE_FAMILY, family);
        nftnl_rule_set_str(r, NFTNL_RULE_CHAIN, chain);
        nftnl_rule_set_str(r, NFTNL_RULE_TABLE, table);
-       nftnl_rule_set_u64(r, NFTNL_RULE_POSITION, handle);
+       nftnl_rule_set_u64(r, NFTNL_RULE_HANDLE, handle);
        nftnl_rule_nlmsg_build_payload(nlh, r);
        nftnl_rule_free(r);
 
@@ -248,24 +248,21 @@ static void trace_print_rule(const struct nftnl_trace *nlt, struct cb_arg *args)
        }
 
        portid = mnl_socket_get_portid(nl);
-        if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
-                perror("mnl_socket_send");
-                exit(EXIT_FAILURE);
-        }
+       if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+               perror("mnl_socket_send");
+               exit(EXIT_FAILURE);
+       }
 
        ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
-        while (ret > 0) {
+       if (ret > 0) {
                args->is_event = false;
-                ret = mnl_cb_run(buf, ret, 0, portid, rule_cb, args);
-                if (ret <= 0)
-                        break;
-                ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
-        }
-        if (ret == -1) {
-                perror("error");
-                exit(EXIT_FAILURE);
-        }
-        mnl_socket_close(nl);
+               ret = mnl_cb_run(buf, ret, 0, portid, rule_cb, args);
+       }
+       if (ret == -1) {
+               perror("error");
+               exit(EXIT_FAILURE);
+       }
+       mnl_socket_close(nl);
 }
 
 static void trace_print_packet(const struct nftnl_trace *nlt, struct cb_arg *args)
@@ -531,6 +528,7 @@ static int trace_cb(const struct nlmsghdr *nlh, struct cb_arg *arg)
 err_free:
        nftnl_trace_free(nlt);
 err:
+       fflush(stdout);
        return MNL_CB_OK;
 }